Myerson Photo Blog

A lot of folks first getting into digital imaging get tripped up on the concept of DPI - dots per inch - or resolution. I’ve been asked before, “What kind of resolution should I be looking for in a camera?”. On the iStockphoto forums, we often hear frustrated buyers ask why an image was 240 DPI instead of 300 DPI. The issue can be confusing at first, but I promise it’s all pretty simple once you get past an important initial understanding:

DPI is arbitrary.

That’s right. It doesn’t matter a whit. It may seem unintuitive. After all, isn’t more resolution better? Isn’t a high-res image priced higher on iStockphoto than a low-res image?

Lets look at some definitions. First off, there’s DPI itself. That’s Dots Per Inch. It represents, as you might expect, the number of dots in each inch of image. The Dots? Another definition. Dots are pixels, the smallest “atomic” unit of a digital image. Each pixel is a point of color. Together these points of color make up an image.

Lets look at a digital image. Take this small shot of a geek. It’s 400 x 400. That is, 400 pixels high and 400 pixels wide. If you were to open this image in Photoshop or similar image editing software, you’d be able to zoom in. And again. And again. Zoom in until you’re viewing this image at 1600x magnification. When you do that, it’s a piece of cake to see the individual pixels (each now as big as a block in this magnification).

So how big is this image? Sure it’s 400×400, but is that as big as a postage stamp? A postcard? A poster? Well, that’s where DPI comes in. When you print this image, your printer will output it at a given resolution, or DPI. That is, your printer will print a certain number of dots per inch. Most desktop printers these days will output somewhere between 300 and 1200 dots per inch. Professional service bureaus may output files as high as 2400 DPI.

That output DPI tells you how large our geek image would be. Lets say we’re using the image in a newsletter, printed at the local copy shop on a laser printer, output at 600 DPI. Our 400 pixel image would be 2/3 inch output at that resolution (400 dots @ 600 dots/inch = 400/600 = 2/3 inch).

2/3 inch is not a very big photo in our newsletter. What can we do? A few things, actually. We can lower the output resolution to 300 DPI. For a newsletter on typical bond paper, there won’t be a noticeable difference between 300 and 600 DPI. Making that change, our little geek grows up to 1.3 inches (400/300). Another option is to use a larger source image. iStockphoto (the only source for that geek image) sells it as large as 2850 x 4230 px. That’s significantly larger. You can also interpolate the image up to a higher pixel count, but that’s not a great idea (and besides, that’s a topic for a future tutorial).

When preparing your files for print, it’s best to match the image DPI to the final output DPI. This is a simple matter in Photoshop. Under the Image menu, select Image Size. From the dialog box that pops up, enter the desired DPI in the resolution box. Be sure to uncheck the “Resample Image” option. That will keep the pixel dimensions the same, and modify just the nominal DPI value. You’ll see what changes is the “Width” and “Height” values. They will decrease as DPI increases, and vice versa.

I hope this introduction to DPI has made some sense. Please feel free to leave a comment in the comment section if I’ve left anything unclear.

I’m happy to be able to mention two upcoming Tucson Photography events in which I’ll be participating in the coming weeks.

The first is a presentation I’ll be giving to the Desert Viewfinders Camera Club (DVCC). This is an organization here in Tucson that has asked me to deliver a talk on stock photography. One of the members of DVCC is also a member of the Tucson Photo Meetup group. I’ll be speaking about how photographers can get started in stock photography, about the prospects for making money in stock photography, and my experiences as an image inspector for iStockphoto.com.

The other exciting event will be the October meeting of the Tucson Photo Meetup group. We meet every month, on the second Saturday of the month. We ordinarily have a member presenting some element of photography, and October’s meeting will be no different; I’ll be bringing my studio equipment to the meeting and doing a seminar on lighting. Some members who already have experience with studio lighting may appreciate this as a refresher, while other members will be experiencing studio strobes for the first time. I’m looking forward to a good seminar, and I’d like to invite any of my readers to come along. It should be a good time.

A third upcoming event is still in the planning stages (so maybe it’s unfair to call it an upcoming event at this point). Several members of the Meetup group will be putting together a group photo shoot, in the spirit of iStockphoto’s “minlypses”. In fact, we’ll be planning our group shoot with the idea of stock photography in mind. Details about this event should develop over the next month or so.

Corporate headshots have become a personal favorite area of photography. It may sound contradictory, but there’s a certain freedom in the limitations imposed by the realities of the shoot. Maybe not a freedom, per se, but certainly a degree of creativity that comes from the scenario.

The limitations in a corporate head shot session are many. The main one is that your time is dictated by the availability of people who are very busy and not very inclined to make time for a photo shoot. CEOs are no different from the rest of the world - given the choice between a conference call and smiling for the camera, the conference call will win every time.

Beyond the time factor, however, there are other limitations. The shoot will almost always be on-site at their offices, and their offices will often not be what they want to have published. Again going with the “CEOs are no different” theory, the desks of busy people tend to look, well, busy. That’s not always the makings of great photos.

So I was very fortunate when I did a recent photo shoot with the executive committee of Ventana Medical Systems in Oro Valley, AZ. The company needed headshots of the CEO, CFO, and COO - both individually and as a group and in two different sets. We did the studio background first. The background shown in the image at left is a white vinyl window shade (click the image for a larger view). We used several different color gels until we found a backdrop that made everyone happy.

After the individual shots, we shot the three CxO’s as a group. For this, we decided the easiest and best option would be isolated against a white background. That had its own set of challenges, mainly the height differences among the three men. One of the things I love about commercial photography is that many times it’s more about problem solving and engineering solutions than about aesthetics. I suppose that appeals to my inner geek.

Another great meetup with some great photographers. I’m really enjoying this group, and I love seeing it grow. Each month we see some returning members as well as some new faces. It’s really cool.

This month saw some fantastic train themed photography, as our challenge theme was trains and railways. The challenge winner wasn’t able to make it, so we had to select next month’s theme without her. We decided to go with “Autumn” - in honor, I suppose, of the fact that we don’t really see any visible signs of the change in seasons; Other than the Tucson temperatures going from sweltering hot to just regular hot.

Several of us decided it would be fun to put together a group photo shoot. I’m looking forward to doing that. We’ll round up some models, get a location, pick a theme, and go for it. Those group events are always a lot of fun, and the group that wants to put it together seems like it will be a good group of Tucson photographers.

Other than that, we spent some time discussing the Tucson market for photography, how each of us handles providing thumbnails for portrait photography clients, watermarking thumbnails, and more.

This weekend should be a good one for generating some new images for my stock photography portfolio. As an image inspector for iStockphoto, I try to inspect as many images as possible on the weekends. This weekend, however, it looks like iStockphoto is undergoing some server maintenance, so it’ll be a perfect time for me to generate some new portfolio pieces. I don’t have anything scheduled with professional models, however, so I’ll be shooting one of two options:

Option 1: family and self portraiture. Not a bad option, because my son is adorable and my wife is both adorable and very pregnant. That leads to some good photo possibilities. I’m myself neither adorable nor pregnant, but I take direction well.

Option 2: product photography. Some of my best selling images on iStock are product shots. It’s an easy way to generate some assets. There’s no one to hire, no one to get tired of smiling and posing, and I can keep shooting until I get tired. I’ve never had a golf club or basketball ask to “take five”.

There’s a third option, as well, which would be to generate non-photographic assets. I have several 3D renderings and vector illustrations available in my iStock portfolio. Those tend to be rewarding, both artistically and financially, but often take much longer to create than photos.

We’ll see which direction this weekend goes.